The vast majority of insect screens, security screens and the like, employ a hollow extruded frame having a channel in which an edge of the screen is secured.
Some arrangements employ a ratchet type mechanism to secure the screen in place and in some cases also apply tension. Australian patent application 78780/98 to Rezon Pty Ltd describes a security screen where a rigid mesh has an edge flange folded back at an acute angle forming a V-shaped edge in section. This edge is inserted into a channel in a frame with ribs forming shoulders extending along one wall of the channel. When the V-shaped screen edge is inserted into the channel, the flange rides over the ribs and then springs back with the edge of the flange retained behind one of the shoulders. A V-shaped filler strip is inserted into the channel behind the flange. This is a simple arrangement and separate fasteners are not required. Australian patent application No 200037825 to W.A. Security Products Pty Ltd describes a security screen where the screen edge has a 90 flange and a locking strip holds the edge in a channel of a frame. A ratchet type arrangement is employed where the locking strip is pushed into the channel behind the screen flange, the locking strip has teeth which jump over teeth on one channel wall in ratchet fashion while teeth on the other channel wall are urged into apertures in the screen. This arrangement utilises some of the principles of 78780/98 but introduces a locking member effectively operating similar to the acutely angled flange. Again there are no conventional fasteners used.
Other arrangements use conventional fasteners. Australian patent application No 25039/93 to Pepperell et al describes a security screen where a screen edge portion is clamped using spaced fasteners and a clamping strip the fasteners passing through the clamping strip, screen and opposite side frame member. Australian patent application No 25040/95 uses spaced rivets and a clamping strip to secure the screen in a frame. Australian patent application No 68121/96 uses spaced rivets which pass into screen apertures and block removal of the screen but the fasteners don't pass all the way though the screen.
Other arrangements employ a combination of wedge, clamp and/or ratchet type methods to secure the screen in a frame. Australian patent application No 71855/98 employs a frame having a channel which is dovetail shaped in cross-section, a slotted insert having inter-digital ribs on opposite walls of the slot fits into the channel and when an edge portion of the screen is pushed into the insert, the insert expands against the dovetail and the screen is held by the ribs. WO9942694 to Security Investments Pty Ltd is similar to 71855/95 except instead of dovetail channel, the channel has teeth on opposite walls and the slotted insert has teeth on outer walls so that there is a combination of the expandible insert and a ratchet used.
Other arrangements use a hand insertable snap-on clamp. Australian patent application No 2003244563 to Moonbush Pty Ltd utilises an L-shaped clamp which snaps into a frame, a settable material surrounds a marginal edge portion of the screen and the screen and settable material sandwiched between the frame and the clamp.
Australian patent No 776083 to Reid describes various screen securing methods whereby a straight screen edge is sandwiched between two parts, a third element is used to urge the two sections to apply force to the screen. This third element may employ a ratchet arrangement, a screw fastener or a wedge or a combination of these. The third element acts on the screen indirectly through one or both of the two parts.
There are a host of solutions to the problem of securing a screen in a channel. The art is clearly a crowded one. In one case the screen is clamped, in another case spaced fasteners are used, in still other cases a fastenerless arrangement is used and still further various combinations of ratchet type arrangements, fasteners and clamps are employed.
All these arrangements have been used commercially with varying levels of success and reliability. Each has its own form of complexity both in construction and installation requirements. Consequently, it is an object of the present invention to at least provide a useful alternative to the prior art and more particularly in the applicant's view a simpler arrangement both in terms of manufacture and installation, the present case simplicity being an inventive element in the combination claimed in an otherwise crowded art.